1. Field of the Invention
Embodiments of the invention concern methods and devices for creating at least one expansion of an association message for wireless mesh networks.
2. Background of the Related Art
WO 2008/122674 A2 relates to a method for operating a mesh-type network, specifically according to IEEE standard 802.11s, wherein the mesh network comprises a plurality of network nodes. From this it is known that six addresses are to be used in the data packets. As FIG. 1 shows, the 5th and 6th addresses E1 and E2 are used to store the MAC addresses of source nodes and sink nodes located outside the WLAN mesh network. The MAC addresses consist preferably of six octets which in turn consist of eight bits.
In this context, methods were proposed to show how a path calculation in the standard routing protocol of IEEE 802.11s, “Hybrid Wireless Mesh Protocol (HWMP)” may be used to route the connection between external nodes, i.e. network nodes which are not mesh nodes and therefore are located outside the mesh network and the corresponding mesh edge nodes, located next to these external nodes. These methods are, however, only suitable for long-lasting images (associations) between the external nodes and the mesh edge nodes. In particular, a mobility of stations STA_A_1 through STA_A_5, STA_B_1 through STA_B_4, STA_C_1 through STA_C_2, STA_D_1 through STA_D_2, STA_E_1 through STA_E_2, STA_F_1 and STA_G_1, which are connected respectively with the mesh access points MAP_A, MAP_B through MAP_G, but can switch from one mesh access point to the next, as shown in FIG. 2 by the mobile station STA_A_1 through STA_G_1 at the mesh access points MAP-A through MAP_G, is inadequately supported.
The proposed “Radio-aware Optimized Link State Routing (RA-OLSR)” protocol, which is an optional, proactive routing protocol of IEEE standard 802.11s [1, Section 11A.7], uses a proactive mechanism, to announce all associations between stations and mesh access points to all other mesh nodes. Each mesh access point has a locally known database, the so-called “local association base” (LAB), containing all stations associated with this mesh access point. The content of these local databases is periodically sent to all nodes in the mesh network, using so-called local association base announcement (LABA) messages. These messages store the data from the received messages in their so-called “global association base” (GAB) and thus they know to which mesh access point data packets addressed to certain stations need to be routed.
If a station switches from one mesh access point to another, the changes will be announced in the RA-OLSR-mesh network, at the latest in the next periodic LABA message. As shown in the drawing in FIG. 2, this means that the LABA message of the old mesh access point of the mobile station no longer contains the address of the mobile station and that the LABA message of the new mesh access point of the mobile station now contains the address of the mobile station.
Standard IEEE 802.1 which is currently being developed is WLAN Mesh Networking, Version “IEEE P802.11s™/D2.O Draft STANDARD for Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications, Amendment <number>: Mesh Networking”. March 2008, pages I-XVII and 1-242—in the following called IEEE P802.11s/D2.0 Draft-Standard—in section “11 B.7.5 Proxy protocol” (pages 180-181) also describes elements for a so-called proxy protocol. These two proxy protocol messages, the so-called proxy update message (or association message) and the proxy update confirmation message (or association confirmation message) are to provide a general means for the any distribution of proxy information (or association information) in a wireless mesh network.
An association comprises an external node and a mesh node. This mesh node is called Proxy Mesh Point or Proxy MP and constitutes the mesh node where data packets of the external node enter the wireless mesh network (Ingress Proxy MP) or where data packets addressed to the external node exit the wireless mesh network (Egress Proxy MP). The Ingress Proxy MP particularly has to know to which Egress Proxy MP the data packets need to be routed.
The association messages in IEEE 802.11s are independent messages by definition and can be used by any routing protocol. In this situation, the routing protocol has to determine when and how the association messages are used, since the associations are part of the routes.
In WO 2008/122674 A2 a mesh network is shown, which explains the mode of operation of such a mesh network in conjunction with FIG. 3 below. This network only shows those mesh edge nodes needed for the explanation, e.g. a first mesh edge node MI, a second mesh edge node M2, a third mesh edge node M3 and a fourth mesh edge node M4. The mesh network can contain many more mesh nodes than those depicted. The paths between the two mesh edge nodes shown may pass via several mesh nodes. For the purpose of clarity, only one external source node SI and one external sink node DI have been extracted from the usually numerous external nodes. Between them and the corresponding mesh edge nodes MI . . . M4 there may be more nodes also.
For the mesh network depicted, it is defined that “external node” refers to those network nodes which are not mesh nodes and therefore outside the mesh network.
Furthermore, “mesh edge node” refers to a mesh node, which in addition to having connections to other mesh nodes also has connections to nodes that do not belong to the mesh network. In the context of IEEE 802.11s, these may be “mesh access points” with which regular WLAN stations (user nodes) may connect for communication via the mesh network or so-called “mesh portals” that have a connection to other networks, e.g. a wired Ethernet.
A mesh edge node used to connect an external source node with the mesh network is also called a mesh source node. A mesh edge node used to connect an external sink node with the mesh network is also called a mesh sink node.